The pop icon, 65, was rushed to hospital last June and forced to reschedule the North American leg of The Celebration Tour, marking the 40th anniversary of her musical career.

Opening the first of five performances at the Kia Forum in Los Angeles, Madonna said the illness was a "surprise" and thanked a "very special man" in the audience, her doctor David Agus.

"When I was sick this summer, and I literally couldn't walk from my bed to the toilet," she said.

"I would call him every other day and ask him why I didn't have any energy, when my energy was going to come back, when was I going to feel myself again, when could I go back on tour again.

"All he would say is, 'go outside in the sun, you need vitamin D, and your kidneys will keep working'."

She described the ordeal as "pretty scary" and revealed the first word she said when she woke from her coma.

"I didn't know for four days because I was in an induced coma, but when I woke up, the first word I said was, 'no'," she said, adding that's what her assistant told her.

"And I'm pretty sure God was saying to me, 'you want to come with us? You want to come with me? You want to go this way?' And I said, 'no, no'."

Recalling her difficult recovery journey, she said it was "so hard" to walk from her house to the garden to sit in the sun.

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"I didn't know when I could get up again and when I could be myself again," she added.

"It was a strange thing to finally not feel like I was in control. That was my lesson to let go."

The Queen of Pop also previously praised her six children for supporting her while she was ill.